1. Technical Field
The present invention relates to a target recognition system to recognize a recognition target area indicating an oncoming car and pedestrian, and a target recognition method executed by the target recognition system.
2. Related Art
At present, recognition systems, installed in vehicles, which recognize obstacles based on a captured image of the area ahead of the vehicle are widely used for driver support systems such as adaptive cruise control (ACC), to reduce the burden on the driver. The driver support systems provide various functions, including a brake-control-and-alert function that alerts the driver to take corrective action to avoid a collision or reduce the impact of the collision, a driving speed adjustment function to maintain a safe minimum distance between vehicles, and a stray prevention function to prevent the vehicle from straying into another lane.
In JP-2008-146549-A, a driver support system that attempts to alleviate the burden on the driver of the vehicle by recognizing targets based on the image of scenery ahead of the vehicle captured by the imaging devices is disclosed. In order to recognize the targets shown in the captured image, the color and spatial frequency of the target are detected from the captured image. By integrating the detected spatial frequency for generating a distribution of the spatial frequency, the characteristics of the spatial frequency are detected. Then, the recognition target is recognized by comparing the detected target color and spatial frequency characteristics with predetermined target color and spatial frequency characteristics.
In order to implement the driver support system, it is necessary to recognize obstacles in the way of the vehicle accurately and immediately. However, in the above-proposed example, the driver support system also detects various targets other than the road, such as buildings, that are less likely to be obstacles. Since these buildings are not considered obstacles like pedestrians and vehicles, detecting targets other than those on the road comes to nothing. Accordingly, recognizing real obstacles on the road becomes slower.
In addition, the processing time required for detecting and integrating the spatial frequency depends on the memory processing ability and can be lengthy. As a result, the recognition processing to detect the real obstacle when the vehicle is traveling is delayed, which makes it difficult to implement the driver support system suitably. In addition, the above-described driver support system recognizes a false target that is less likely to function as the real obstacle of the recognition target in the background ahead. Therefore, the system may mistakenly recognize background targets as recognition targets.